Within Session P300

This example shows how to perform a within session analysis on three different P300 datasets.

We will compare two pipelines :

• Riemannian geometry

• XDAWN with Linear Discriminant Analysis

We will use the P300 paradigm, which uses the AUC as metric.

# Authors: Pedro Rodrigues <pedro.rodrigues01@gmail.com>
#
# License: BSD (3-clause)

import warnings

import matplotlib.pyplot as plt
import seaborn as sns
from mne.decoding import Vectorizer
from pyriemann.estimation import Xdawn, XdawnCovariances
from pyriemann.tangentspace import TangentSpace
from sklearn.discriminant_analysis import LinearDiscriminantAnalysis as LDA
from sklearn.pipeline import make_pipeline

import moabb
from moabb.datasets import BNCI2014_009
from moabb.evaluations import WithinSessionEvaluation
from moabb.paradigms import P300

getting rid of the warnings about the future

warnings.simplefilter(action="ignore", category=FutureWarning)
warnings.simplefilter(action="ignore", category=RuntimeWarning)

moabb.set_log_level("info")

Create Pipelines

Pipelines must be a dict of sklearn pipeline transformer.

pipelines = {}

We have to do this because the classes are called ‘Target’ and ‘NonTarget’ but the evaluation function uses a LabelEncoder, transforming them to 0 and 1

labels_dict = {"Target": 1, "NonTarget": 0}

pipelines["RG+LDA"] = make_pipeline(
    XdawnCovariances(
        nfilter=2, classes=[labels_dict["Target"]], estimator="lwf", xdawn_estimator="scm"
    ),
    TangentSpace(),
    LDA(solver="lsqr", shrinkage="auto"),
)

pipelines["Xdw+LDA"] = make_pipeline(
    Xdawn(nfilter=2, estimator="scm"), Vectorizer(), LDA(solver="lsqr", shrinkage="auto")
)

Evaluation

We define the paradigm (P300) and use all three datasets available for it. The evaluation will return a DataFrame containing a single AUC score for each subject / session of the dataset, and for each pipeline.

Results are saved into the database, so that if you add a new pipeline, it will not run again the evaluation unless a parameter has changed. Results can be overwritten if necessary.

paradigm = P300(resample=128)
dataset = BNCI2014_009()
dataset.subject_list = dataset.subject_list[:2]
datasets = [dataset]
overwrite = True  # set to True if we want to overwrite cached results
evaluation = WithinSessionEvaluation(
    paradigm=paradigm, datasets=datasets, suffix="examples", overwrite=overwrite
)
results = evaluation.process(pipelines)

BNCI2014-009-WithinSession:   0%|          | 0/2 [00:00<?, ?it/s]/home/runner/work/moabb/moabb/moabb/datasets/preprocessing.py:278: UserWarning: warnEpochs <Epochs | 576 events (all good), 0 – 0.801 s (baseline off), ~14.5 MB, data loaded,
 'Target': 96
 'NonTarget': 480>
  warn(f"warnEpochs {epochs}")
/home/runner/work/moabb/moabb/moabb/datasets/preprocessing.py:278: UserWarning: warnEpochs <Epochs | 576 events (all good), 0 – 0.801 s (baseline off), ~14.5 MB, data loaded,
 'Target': 96
 'NonTarget': 480>
  warn(f"warnEpochs {epochs}")
/home/runner/work/moabb/moabb/moabb/datasets/preprocessing.py:278: UserWarning: warnEpochs <Epochs | 576 events (all good), 0 – 0.801 s (baseline off), ~14.5 MB, data loaded,
 'Target': 96
 'NonTarget': 480>
  warn(f"warnEpochs {epochs}")
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.

BNCI2014-009-WithinSession:  50%|#####     | 1/2 [00:09<00:09,  9.81s/it]/home/runner/work/moabb/moabb/moabb/datasets/preprocessing.py:278: UserWarning: warnEpochs <Epochs | 576 events (all good), 0 – 0.801 s (baseline off), ~14.5 MB, data loaded,
 'Target': 96
 'NonTarget': 480>
  warn(f"warnEpochs {epochs}")
/home/runner/work/moabb/moabb/moabb/datasets/preprocessing.py:278: UserWarning: warnEpochs <Epochs | 576 events (all good), 0 – 0.801 s (baseline off), ~14.5 MB, data loaded,
 'Target': 96
 'NonTarget': 480>
  warn(f"warnEpochs {epochs}")
/home/runner/work/moabb/moabb/moabb/datasets/preprocessing.py:278: UserWarning: warnEpochs <Epochs | 576 events (all good), 0 – 0.801 s (baseline off), ~14.5 MB, data loaded,
 'Target': 96
 'NonTarget': 480>
  warn(f"warnEpochs {epochs}")
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.
No hdf5_path provided, models will not be saved.

BNCI2014-009-WithinSession: 100%|##########| 2/2 [00:19<00:00,  9.74s/it]
BNCI2014-009-WithinSession: 100%|##########| 2/2 [00:19<00:00,  9.75s/it]

Plot Results

Here we plot the results to compare the two pipelines

fig, ax = plt.subplots(facecolor="white", figsize=[8, 4])

sns.stripplot(
    data=results,
    y="score",
    x="pipeline",
    ax=ax,
    jitter=True,
    alpha=0.5,
    zorder=1,
    palette="Set1",
)
sns.pointplot(data=results, y="score", x="pipeline", ax=ax, palette="Set1")

ax.set_ylabel("ROC AUC")
ax.set_ylim(0.5, 1)

plt.show()

Estimated memory usage: 51 MB